Atrazine does not induce pica behavior at doses that increase hypothalamic–pituitary–adrenal axis activation and cause conditioned taste avoidance

• Published in: Neurotoxicology and teratology Vol. 34; no. 3; pp. 295 - 302
• Main Authors: Hotchkiss, Michelle Gatien, Best, Deborah S, Cooper, Ralph L, Laws, Susan C
• Format: Journal Article
• Language: English
• Published: New York, NY Elsevier Inc 01.05.2012; Elsevier
• Subjects: Adrenocorticotropic Hormone - blood; Animals; Atrazine; Atrazine - toxicity; Avoidance Learning - drug effects; Behavior, Animal - drug effects; Biological and medical sciences; Conditioned taste avoidance; Conditioning (Psychology) - drug effects; Corticosterone - blood; Diamino-s-chlorotriazine; Dose-Response Relationship, Drug; Emergency; Herbicides - toxicity; Hypothalamic–pituitary–adrenal axis; Hypothalamo-Hypophyseal System - drug effects; Male; Medical Education; Medical sciences; Pesticides, fertilizers and other agrochemicals toxicology; Pica - chemically induced; Pica behavior; Pituitary-Adrenal System - drug effects; Progesterone - blood; Rats; Rats, Wistar; Taste - drug effects; Toxicology; LiCl; National Health and Environmental Effects Research Laboratory; Hypothalamic–pituitary–adrenal axis; ACTH; LOEL; stress-induced hyperthermia; NOEL; adrenocorticotropic hormone; conditioned taste avoidance; maximum contaminant level; analysis of variance; no dose; ANOVA; lithium chloride; hypothalamic–pituitary–adrenal; NHEERL; EST; Eastern Standard Time; RIA; Pica behavior; CORT; CTA; DACT; SIH; radioimmunoassay; no observable effect level; atrazine; ND; MCL; HPA; SEM; standard error of the mean; corticosterone; diamino-s-chlorotriazine; lowest observable effect level; ATR; Diamino-s-chlorotriazine; Conditioned taste avoidance; Atrazine; Hypothalamohypophysoadrenal axis; Pesticides; Hypothalamic-pituitary-adrenal axis; Increase; Eating disorder; Herbicide; Pica; Triazine derivatives; Behavior; Dose; Avoidance
• ISSN: 0892-0362; 1872-9738
• DOI: 10.1016/j.ntt.2012.03.001

Abstract Previous work has shown that a single oral administration of atrazine (ATR), a chlorotriazine herbicide, causes rapid increases in plasma adrenocorticotropic hormone (ACTH), serum corticosterone (CORT) and progesterone. The mechanism for these effects is unknown. To test whether administration of ATR causes hypothalamic–pituitary–adrenal (HPA) axis activation through the production of a generalized stress response resulting from gastrointestinal distress, we conducted both conditioned taste avoidance (CTA) and pica behavior experiments. Body temperature data were also collected to detect the presence of stress-induced hyperthermia. Adult male Wistar rats were given a single oral dose of ATR (0, 5, 25, 50, 100, or 200 mg/kg) or the primary ATR metabolite diamino-s-chlorotriazine (DACT; 135 mg/kg). Increases were observed in ACTH (LOEL, 12.5 mg/kg), CORT (LOEL, 5 mg/kg) and progesterone (LOEL, 5 mg/kg) 15 min following a single dose of ATR. DACT (135 mg/kg) increased ACTH (1.3-fold), CORT (2.9-fold) and progesterone (1.9-fold) above vehicle control concentrations, but the magnitude of the responses was much lower than that observed for an equal molar dose of ATR (200 mg/kg; 7.0, 9.0 and 11.0-fold above ACTH, CORT, progesterone controls, respectively). CTA results demonstrated conditioned taste avoidance to ATR, with a NOEL of 5 mg/kg. Animals dosed with DACT developed avoidance responses comparable to the highest dose of ATR. In the pica experiment, lower doses (5–50 mg/kg) of ATR had no effect on pica behavior, as measured 6 and 24 h post-dosing, nor did DACT. However, the highest dose of ATR (200 mg/kg) did induce pica behavior at both time points. No differences in body temperature were observed. Overall, results indicate that increases in ACTH and CORT secretion following administration of ATR occur at doses that are without effect on the display of pica behavior, indicating that the HPA-axis activation caused by ATR is not likely the result of gastrointestinal distress.